FIG. 1 shows a simple motor system, indicated generally by the reference numeral 1. The motor system 1 comprises a three-phase motor 2, an AC power source 4, a converter 6, an inverter 8 and a control module 10.
The output of the AC power source 4 is connected to the input of the converter 6. The converter 6 rectifies the AC input from the AC power source 4 (the converter 6 may be a rectifier, although alternatives, such as an active front end, are possible). The rectified output of the converter 6 provides DC power to the inverter 8. In a manner well known in the art, the inverter module includes a switching module, typically comprising insulated gate bipolar transistors (IGBTs) that are driven by gate control signals in order to convert the DC voltage into an AC voltage having a frequency and phase dependent on the gate control signals. The gate control signals are provided by the control module 10. In this way, the frequency, phase and amplitude of each input to the motor 2 can be readily controlled.
The inverter 8 is in two-way communication with the control module 10. The inverter typically monitors currents and voltages in each of the three connections to the motor 2 and provides that current and voltage data to the control module 10 (although the use of both current and voltage sensors is by no means essential). The control module 10 may make use of the current and/or voltage data (where available) when generating the gate control signals required to operate the motor as desired; another arrangement is to estimate the currents from the drawn voltages and the switching pattern—other control arrangements also exist.
The motor 2 may take many different forms. Exemplary motor types include induction motors, synchronous reluctance motors and various forms of permanent magnet motors. Different motor types typically require different control algorithms. In the event that the system 1 allows the type of the motor 2 to be changed, then in order for the system 1 to control the motor 2, it is necessary to identify the motor type.
It is known for a motor commissioning algorithm to require a technician to manually input the motor type being used. It is possible for the technician to input the wrong type of motor, with the result that the motor is not correctly controlled. In some circumstances, this could result in the motor operating inefficiently. In other circumstances, this could result in the motor failing to operate at all.
There remains a need for providing improved or alternative approaches for the identification of motor types.
The present invention seeks to address at least some of the problems outlined above.